The objectives of this project are to define and generate filarial proteins that are important in inducing parasite-specific immune responses in the human host and to understand, at a molecular level, the differences among related filarial species. Recombinant antigens and probes have been identified that: a) encode immunoreactive and potentially protective molecules of W. bancrofti; b) can distinguish among related filarial species; c) identify repeated segments of either the W. bancrofti genome or that of Loa loa; d) may be of potential diagnostic importance; and e) induce immediate hypersensitivity type responses in lymphatic filarial syndromes.